There are only a few things that require crystals as of .7.0, but ther will most likely more uses in the future. What things might come, I don't know, most people wouldn't, and anyone who did know won't tell, so it is a waiting game for now.

Personaly, I saved all 8, I figure it's best to wait and have to spend them later than it is to be sitting there later wishing I had saved them.

You receive the first weapon and armour proficiency skills for free. So, presumably you chose toy favourite and best suited for tour characters game play style. So purchasing more means you've changed your mind or tour wanting a character with multiple styles (costly).

I'd wait until you've complete as much as you wish of the game, and picked up whatever Legendary equipment you intend to grind for. Then fork your save games, keep a savegame before spending the crystals and another to carry on. Gives you a place to go back to if better uses for savegames come up in future releases.

Covenant wrote:You receive the first weapon and armour proficiency skills for free. So, presumably you chose toy favourite and best suited for tour characters game play style. So purchasing more means you've changed your mind or tour wanting a character with multiple styles (costly).

Sort of. I'm Duel Wielding. I was originally going for a high crit build (+66, x3.0 w/ current equipment). I was wielding Dagger of the Shadow Priests and Flagstone's Pride (one dagger, one sword). I was using two Balanced Steel Swords on creatures immune to crits (two swords). So I chose the sword proficiency. However, I've discovered that I really like two Quickstrike Daggers instead.

So, now I wish I had chosen the dagger proficiency.
And the only save I have prior to that is 20 levels lower than were I'm at now.

As far as i can tell i have gained theses crystals from i guess you could call them bosses.i found only one use for them and that is geting skills from charwood cabin.i like realy need to know if this map is going to be updated.i beat the whole thing.i got lodars speacial poitions and found the missing boy and all that jazz everyone said i couldn't do yet.i scoured every inch of map and killed everything three hundred times over if i have killed it once.i havnt played in a bit because I'm at a complete stuck point.